The present invention relates in general to an alarm device for a vehicle such as a motor car, an electric car or a motor cycle. In particular, the invention concerns an alarm device for a motor vehicle which is intended for generating alarms upon occurrence of abnormalities or abnormal states of various equipments of the vehicle to thereby inform the occupants or passenger of the abnormalities.
Alarm devices for motor vehicles have heretofore been known and are widely employed with a view to assuring security of the occupants of the vehicle and/or protecting the occupants and the vehicle from accidents and failures to thereby secure safety in the operation of the motor vehicle. To this end, the alarm device is so constructed as to detect occurrence of abnormal states of equipments, parts and/or operating conditions to inform the occupant of them. More specifically, means for detecting occurrence of the abnormalities such as various types of sensors which respond to variations in physical quantities such as pressure, temperature, liquid temperature and so forth are provided at those locations where occurrence of abnormal states will possibly lead to serious accidents or failures. The output signals available from these sensors are evaluated and utilized to activate alarm lamps, buzzers or the like to inform the occupant(s) of the vehicle of the occurrence of the abnormal state or states. However, the hitherto known alarm devices suffer poor reliability in operation, that is, the occurrence of an abnormal state can not always be reported to the driver of the vehicle in a proper manner. For example, in the case of the motor vehicle, the driver has to keep his attention to the front, the rear and the sides of the motor car. Under the circumstance, it is difficult for the driver to pay constant attention to all the numerous alarm display lamps. Thus, an alarm may sometimes escape the driver's notice or be noticed too late. When buzzers are employed for generation of alarms, it is difficult to discriminate the kinds of alarms and hence the natures of the detected abnormal states in dependence on the tone of the sound generated by the buzzer. In practice, the buzzer is used only for producing a specific alarm.
As an attempt to overcome the shortcomings of the alarm lamp and buzzer described above, it may be conceived that the occurrence of an abnormal state is reported to the driver in the case of the motor vehicle through the medium of human speech. Needless to say, the function of the alarm device resides in checking the states or conditions of the equipments (such as the brake system and the like) which play an important role in securing the safe operation of the vehicle, equipments for assuring normal operation of the engine (such as engine oil pressure) and the equipment for assuring security of the occupant(s) (such as seat belts) and sending information on the result of the checks to the occupants without fail. In this connection, the alarm which resorts to the use of human speech and thus can appeal to the auditory sense of the driver is able to inform the driver of the occurrence of an abnormal state with an enhanced reliability. However, when two or more kinds of the alarm speeches are produced simultaneously, the driver will find it difficult to understand the produced alarms discriminatively, involving a problem in assuring safety, unlike the case where alarm lamps are used. For producing the alarm by making use of the human speech, there have hitherto been required audio reproducing apparatus such as magnetic tape and disc type playback apparatus which are however not only voluminous and expensive but also susceptible to malfunctions in adverse environmental conditions such as in a motor vehicle where large vibrations are generated and ambient conditions such as temperature and humidity undergo significant variations. For these reasons, the alarm device using the audio reproducing apparatus has not yet been practically used.